As one kind of compaction roller, a self-propelled ride-on type vibration tire roller, which roller has the front and rear wheels, at least one of which is constituted of tires, is known (see the JPA Publications No. H09-31912 and No. 2003-184022). In the vibration tire roller of the JPA Publication No. H09-31912, there is no differential mechanism so the right side tires and left side tires thereof cannot rotate different speeds in a compaction operation in a curve, and the surface to be compacted can be damaged. Also, since a distance from the outside surface of the most outside tire to a tire support member situated on the side portion of a vehicle body, a so-called side overhang is large, compaction in the vicinity of a road incidental structure is impossible.
Meanwhile, in the JPA Publication No. 2003-184022, a technology in which a tire support member is interposed between adjoining tires and a traveling motor for tire driving is mounted on the tire support member is disclosed. According to this technology, while there is right and left differential mechanism, interposition of the tire support member between the tires eliminates the need to dispose the tire support member outwardly of the most outside tire, thereby enabling reduction of the side overhang. Thus, advantageously, the most outside tire can be put further accordingly closer to the road incidental structure for compaction.
This technology provides a structure that, a vibration device is extended between paired right and left tire support members, and each tire support member is interposed outer side tire and inner side tire, of four tires. In this structure, vibrations can be transmitted efficiently to the two inside tires but are hard to be transmitted to the two outside tires. Thus, vibration differences tend to occur between four tires.